There’s gold all around us, embedded in our electronics. There are people who collect e-waste and use various methods to extract gold from them. However, it is hard to qualify it as a “get rich quick” scheme because the amount of gold recovered is usually minute. Still, if you can do volume, you can make some money and recycling is always a good idea. At the University of Manchester, they have a better way to extract gold from e-waste using graphene. You can see a brief video about the process below, or read the full paper.
The process is relatively simple. You dissolve the e-waste in a solvent, add some graphene oxide, and the gold appears bound to the graphene. You pull out the graphene and burn it off to result in the gold you want. A gram of graphene can grab 2 grams of gold and graphene is relatively cheap per gram compared to gold.
Graphene oxide nanosheets are processed using ascorbic acid into a colloid suspension. The chemical process converts gold bound with chlorine into elemental gold. After diving into why the process works, they were able to increase the selectivity of the process by manipulating the pH so that the majority of the residue is actually gold.
The team believes they can build a continuous process that takes liquefied e-waste and extracts gold as it flows through the system. If you’d rather go with the traditional method, here’s a start for you. Then again, there are other metals to recover besides gold.
“The chemical process converts cold bound with chlorine into elemental gold.” So the philosophers stone was just ICE all along?! :O omg!! Ciao, I’m moving to Alaska!
Yes, that’s why there is so much gold in Alaska…
+1
Imagine this liquid mixture pumped through rock to extract gold. Say, you go to an area that’s deemed not viable, because the percentage of gold is too low for mining and now you have a method of squeezing every last drop out.
I wonder if this could be modified for extracting other metals, there are several rare and expensive things in modern smartphones etc. It might even make platinum extraction easier from catalytic converters. I guess it beats the aqua regia method, at least slightly better for the environment. I also wonder about it’s use in medicine for treating metal poisoning.
This is exceptionally unlikely to have a medical application.
In medicine, they use chemical chelation to bind heavy metal ions with no regard to harvesting the result. It’s extremely effective, biocompatible (very important in medicine), but far harder to process back into the heavy metal.
Fun fact, if you wish to do this process slowly (i.e. avoid leaving your old bones brittle because they were saturated with heavy metal(s) decades ago) then you can be done by simply maintaining a diet that is heavy in sulfur for several months.
A diet heavy in sulfer…
I bet you are very popular in the elevator.
Extracting and processing leachate from mountainsides is how they’re currently getting much of the rare earth metals out of Myanmar. I just read about that last week and the ecological devastation it was causing there. They inject ammonium sulfate solution, then capture and process the runoff, leaving a crumbling toxic stew behind.
I hope a similar method isn’t used for gold extraction. It will only attract the people who are willing to sacrifice ecology for money. Search for “myanmar toxic mines” for more.
^this^
Unfortunately, using chemicals to dissolve metals is how lots of mines work, even in the USA. I once toured a mine in Cripple Creek Colorado and they put the crushed up rocks in leach fields, soak them in toxic chemicals, then process the liquid to pull the gold out (I think it was a sort of electrolysis like system), then recycle the chemicals and purify any water that is disposed of. The big difference is that in the USA, there are rules to make sure it does not contaminate the environment as much.
If I remember right, they were able to reprocess some of the discarded ore that was too low quality when it was originally mined during the gold rush, but most of their ore is dug up fresh.
(The tour was 15+ years ago, but I doubt they’ve changed the process much)
cyanide leaching, and ELECTROWINNING
Still done that way, harder and harder to get permits for new operations so people will keep historical leech sites up and running and truck in fresh ores.
For years they used mercury to leach the gold from ore and then boiled the mercury off, leaving the gold behind.
So, yeah, totally fine and safe. :)
They still use the aqua regia method to get the gold from ground up e-waste in solution, just with a better way of getting it out of the solution.
From the article:
“Real-world gold extraction
A discarded CPU was obtained from computer waste. To leach gold
from the CPU, it was first soaked in an 8 M NaOH solution for two days
to remove the protective coating on the electronic surfaces. Afterwards, the CPU was rinsed and soaked in 40 mL aqua regia at 60 °C for
two days.”
Gold extraction by cyanide used to be economic at ore rates of 1/2 gram gold per tonne of ore. I am sure it is even lower now.
iodine pipe circulating leach with grox filters